1,720,983 research outputs found
Chromatin looping links gene expression to the assembly of transcription factories (Review)
No full text: Genes are not randomly dispersed within the nuclear space, instead they occupy precise sites either with respect to the nuclear lamina as well as to each other. This observation stands at the basis of the today well accepted concept of nuclear territories where any chromosome shows reproducible spatial connections with a selection of others in a general picture that meets a functional criterion where genes that answer the same stimuli are grouped in the same sites. In fact, transcription is not visible widely dispersed throughout the nucleus but is gathered in several 'granules', called transcription factories that accommodates ~10 genes concurrently transcribed. This dynamic behavior of chromosomes is allowed by changes in chromatin plasticity that are governed by several classes of proteins that either modify its building or induce post‐translational modifications in the protein component of nucleosomes, triggering formation of chromosome loops that modify the location of specific sites along the DNA strand. For example, transcription associated to nuclear receptors benefits of the generation of nuclear ROS that induce nicks following activation of the DNA repair apparatus that enhance helix unfolding and chromosome bridging. In the present review, the role that protocols facing elucidation of chromosome architecture are playing and will play in the near future were highlighted in order to investigate composition of the transcription factories assembled in response of a specific trigger: The estrogen‐sensitive transcription was cited but the authors are convinced that the same portrait will be observed with a multitude of (if not all) other stimuli
LSD1: more than demethylation of histone lysine residues
Full text linkLysine-specific histone demethylase 1 (LSD1) represents the first example of an identified nuclear protein with histone demethylase activity. In particular, it plays a special role in the epigenetic regulation of gene expression, as it removes methyl groups from mono- and dimethylated lysine 4 and/or lysine 9 on histone H3 (H3K4me1/2 and H3K9me1/2), behaving as a repressor or activator of gene expression, respectively. Moreover, it has been recently found to demethylate monomethylated and dimethylated lysine 20 in histone H4 and to contribute to the balance of several other methylated lysine residues in histone H3 (i.e., H3K27, H3K36, and H3K79). Furthermore, in recent years, a plethora of nonhistone proteins have been detected as targets of LSD1 activity, suggesting that this demethylase is a fundamental player in the regulation of multiple pathways triggered in several cellular processes, including cancer progression. In this review, we analyze the molecular mechanism by which LSD1 displays its dual effect on gene expression (related to the specific lysine target), placing final emphasis on the use of pharmacological inhibitors of its activity in future clinical studies to fight cancer
17beta-estradiol inhibits apoptosis in MCF-7 cells, inducing bcl-2 expression via two estrogen-responsive elements present in the coding sequence.
No full textIF = 8.8
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Analysis of histone posttranslational modifications in the control of chromatin plasticity observed at estrogen-responsive sites in human breast cancer cells.
No full textIt is well established that histone posttranslational modifications mediate the control of gene expression played by chromatin. Such modifications are commonly reversible and many alternatives are open to drive transcription of inducible genes. Estrogens govern growth and survival of hormone-sensitive cells by inducing expression of genes important for cell cycle progression and apoptosis. Transcription of estrogen-responsive genes is triggered by the lysine-specific demethylase 1 (LSD1)-dependent demethylation of dimethylated lysine 9 in histone H3 (H3K9me2) that accompanies to local generation of oxygen reactive species (ROS). Production of ROS modifies guanines in neighbor DNA with consequent recruitment of base-excision repair (BER) enzymes and formation of breaks that support creation of bridges between sites that, although distant on linear DNA, establish strategic contacts useful for productive transcription
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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